Output coupling for high-frequency oscillators



Nov. 19, 1946. J F|$K 2,411,151

OUTPUT COUPLING FOR HIGH FREQUENCY OSCILLIATORS Filed May 1, 1942 3Sheets-Sheet l 52 22 .30 FIG. 2 24 42 4a 48 W l F T 1 i 3mm Hi I UB9, T30 2: all INVENTOR JBF/SK NW 0. 3/)

ATTORNEY Nov. 19, 1946.

.J. B. FISK 2,411,151

OUTPUT COUPLING FOR HIGH FREQUENCY OSCILLATORS Filed May 1, 1942 3Sheets-Sheet 2 INVENTOR J B. F ISA A T TORNEV NOV. 19, 1946. s 2,411,151

OUTPUT COUPLING FOR HIGH FREQUENCY OSCILLATORS Filed May 1, 1942 3Sheets-Sheet 5 //v l/EN TOR By J. B. F/SK nmpnnf A T TORNE V MM. is,rate OUTPUT OOUPIJIG I03 HIGH-m0! osma'roas hlephone Yorhll. YaeorporationofNewfol-k llaylJMLBer-iall'imfll,

IBM

This invention relates to electron discharge devices and particularly tothose devices termed magnetrons in which high lrequency oscillations areproduced by the curvilinear orbital motions of electric charges underthe Joint influence of electric and mimetic nelds.

An obiect of the invention is to provide simple and eil'ective means forabstracting the power of ammualgnetron and delivering it to autilisation c A related obiect is to efleet such withdrawal or powerabstraction with a minimum of distortion orperturbation of the highfrequency electromagnetic fields which exist within the device durinoperation.

Another object of the invention is to Provide simple and effective meansfor adjusting the frequency of oscillation of the magnetron.

In the development of the magnetron art. an important step which wastaken in an eil'ort to obtain higher oscillation fr quencies than werepossible with the original continuous anode surface, was to subdividethe anode into two halves and connect tuning elements. for example inductance and capacity elements. between them. This practice was thenfurther extended by subdividing the anode surface into four, six, eight,etc. surfaces, alternate ones being conductively connected together. Inall of these arrangements tuning was a comparatively simple matter,being accomplished simply by adjustment of the inductance andcapacitance elements which were normall mounted externally of themagnetron Prop r to desired values.

Further eilorts to extend the oscillation frequency of magnctrons tohigher values were impeded by the limitations inherent in the lumpedtuning elements. Accordingly. the art turned to a modified structuresuch as shown, for example. in Samuel Patent 2,083,342. December 8,1936. in which the external lumped tuning elements are replaced bycavity resonators disp sed within the envelope and close to thedischarge or interaction space itself. being coupled thereto by way ofopenings or channela The discharge space and the tuning cavities mayindeed be machined from a single solid mass which may be mounted withina cylindrical shell and between flat end plates.

This departure permits a considerable increase in operating frequency.However. it presents difflculties in eiiecting an external coupling forthe abstraction of power. Output power coupling to magnetrons of thesolid anode type has heretofore been eii'ected by way of a smallcoupling loop which passes through the outside wall or casing d thedevice into one of the tuning cavityresonatorsandtherelinksaportionofthehigh frequency magnetic flux whichexists therein during operation. when the area of this loop is asubstantial fraction of the cross-sectional area oi the cavity resonatorwith which it is so coupled. the latter is overloaded. with the resultthat severe distortions and perturbations exist in the electromagneticiicld pattern within the device. On the other hand. when the couplingloop area is but a small fraction of the cross-sectional area of thecavity resonator, it links but a correspondingly small fraction of themagnetic flux and sumces to abstract only a correspondingly small amountof power. Furthermore. adjustment of the area or orientation of suchcoupling loop to link more or less of the magnetic flux within thecavity, is beset by such diniculties that it is customary to build thecoupling loop as an integral part of the device. with the result thatthe power abstracted is not subiect to change at the will of theoperator. but can be altered only by a completely new construction basedon a new design.

Devices of this character also suiler from the disadvantage that anyminute error in the dimensions of the resonators or the channels whichinterconnect them with the discharge space causes a corresponding errorin the oscillation frequency which can be corrected only by a completeremachining and reconstruction of the anode structure as a whole.

The present invention is based upon the discovery that in a magnetron ofthe solid anode type the cavity resonators, though geometricallyseparate. are electromagnetically lntercoupled, inasmuch as some of thehigh frequency magnetic llux lines which link any one cavity bend overat the ends or the structures to link other cavities, thus roviding amutual impedance coupling between the members of each pair of adjacentcavities, and providing, also. regions of relatively dense mutual iluxat which desired couplings may be effected, alternating with regions atwhich the mutual flux density is much reduced, at which regionsconductors may be led into the end space without appreciable unwantedcoupling. The magnitude of this mutual impedance as compared with thesell-impedance of each cavity depends. in a highly complex mannor. onall the cavity dimensions. It depends. in particular, on the length andcross section of the mutual flux path between cavities which path isboundedononesidebytheanodestructureand on the other by the end plate ofthe its shortest length being the distance separating adjacent portionsof the open ends of adjacent cavities. By arranging that these adjacentopen cavity ends shall be close together, it has been found possible toproduce a large amount of mutual intercavity flux, and therefore a largemutual impedance coupling between adjacent cavities. As long as theintercavity coupling is greater than a certain critical value. increasesand reductions in the coupling produce corresponding alterations in theresonant frequency of the magnetron, in accordance with principles whichare well known in the coupled circuit art. See, for example, chapter 3of High Frequency Alternating Currents," by McIlwain and Brainerd, 1931edition.

In accordance with a principal aspect of the invention an output powercoupling loop is provided which links only the mutual flux which iscommon to two or more of the cavity resonators. It may extend into theend space oi the magnetron through a suitable seal and make contact withthe anode block in the vicinity of the central discharge space, inposition to link a portion of the flux which is common to two adjacentcavities. Preferably, the loop lies in a plane midway between twoadjacent cavities. Evidently a single such coupling loop interactssimilarly with the electromagnetic fields within the cavities on eachside of it and therefore introduces much less asymmetry into thesefields than would be introduced by a loop coupled exclusively to theflux within one cavity. Furthermore, the amount of flux which is linkedby the loop and the amount of power abstracted may easily be varied byvarying the loop area, for example, by advancing or withdrawing the loopin a radial direction while its end slides over the end of the machinedanode block.

If desired, a plurality of such loops may be provided. They may supplyenergy to a common utilization circuit, phase shifting means beingemployed to adjust the phases of the currents so withdrawn until theyare alike, or. if preierred. the coupling loops may be tuned andemployed as trimmers to adjust the oscillation frequency of themagnetron to a desired value.

On the other hand the central cathode may be supplied with operatingpotential and its heater element with current by way of conductors whichextend radially into the magnetron end space in the plane of the axis ofone of the cavity resonators, about which plane the flux from eachcavity divides substantially equally, half passing to the adjacentcavity on one side and the other half to the adjacent cavity on theother side. With this disposition of the cathode supply conductors thecoupling between them and the high frequency fields is reduced to aminimum, with consequent reduction of high he quency power losses in theconductors.

The invention will be fully understood from the following description ofa preferred illustrative embodiment thereof taken in conjunction withthe appended drawings, in which:

Fig. l is a plan view of a cavity-tuned magnetron provided with aplurality of mutual inductance coupling loops and a cathode supply leaddisposed in accordance with the invention;

Fig. 2 is a broken vertical cross section of Fig. 1;

Fig. 3 is a plan view of a magnetron similar to that of Fig. 1 but inwhich the intercavity coupling has been increased by a reduction of theseparation distance between cavities;

Fig. 4 is a plan view of a magnetron similar to that of Fig. 1 but inwhich the intercavity coupling has been reduced by the use of elongatedcavities;

Fig. 5 is a plan view of a part oi a magnetron similar to that of Fig. 1but in which the intercavity coupling has been further reduced by theemployment of narrow parallel-sided slots as tuning cavities; and

Fig. 6 is an end view of a magnetron similar to that of Fig. l but inwhich certain of the coupling loops are arranged to supply energy to acommon utilization circuit.

Referring now to Figs. 1 and 2, the body of the magnetron may comprise acomparatively massive block ll of conductive material such as copper,into which are cut as by drilling, a central discharge space l2 and aplurality oi resonant cavities ll surroundin the same and symmetricallydisposed about it. Each of the cavities ll opens on to the dischargespace l2 through a channel or slot it which serves as a coupling meansbetween the energy or movement of the electrons in the discharge spacel2 and the electromagnetic held within the cavities ll. The cylindricalsurfaces I8 between channels Ii serve as anode surfaces.

The anode block Iii is preferably mounted centrally in a cylindricalshell or casing of cmductive material such as copper, connected thereto.If preferred, anode block I and shell 20 may be machined from a singlesolid mass. In either case the shell may be closed at the end by plates22 which serve both to exclude air and gases and to define the endspaces 24 in which the mutual flux 26 common to adjacent cavitiesexists. These end plates may be flat, or they may be recessed as shown,the better to concentrate the mutual flux 26 in the vicinity of thecoupling loops to be described.

A central cathode, for example an elongated cylindrical element 28,whose surface is rendered electron emissive by suitable treatment may bemounted centrally in the discharge space l2 and supported in place as byconductive rods 30. To bring it to a state of electron emissiveness,heat may be applied thereto as by a heating element 32 which may beembedded in ceramic material within the cathode 28 and electricallyconnected thereto. The heater 32 may be supplied from any suitablesource such as a battery 34, for example, by way of the cathode supports30 which may be brought into the end spaces 24 through insulating seals38.

In operation the heater leads will be maintained at or close to thecathode potential which is highly negative with respect to the anodeblock ill and the end plates 22 which define the end spaces 24 throughwhich th heater leads Ill reach the cathode 28 and the heater 32. Toavoid asymmetry the electromagnetic fields within the end spaces 24 dueto the presence of the low potential heater leads and also to preventhigh frequency induction therein and consequent power loss, they arepreferably brought into the end spaces in the plane of the axis of oneof the tuning cavities l4. Thus the mutual flux lines 26 emerging fromthe cavity ll pass to either side of the heater leads 3!! in such a waythat only a negligible quantity of this flux links the heater leads. Bythis expedient coupling between the heater leads and the electromagneticflelds in the end spaces may be reduced to a negligible value.

Under certain conditions, the operatingtemperatureorthecathodemaybemaintainedafter theapparatushasheenwellstartedmerelyby bombardment thereof by electronswhich orisi nate on the cathode surface, travel into the discharge spaceand partway through their orbits and return at high velocities to thecathode. The cathode It may he provided with end discs 38 to maintainspace charge conditions within the discharge space at desired values andreduce losses due to the escape of working electrons into the endspacesofthedevica' Operating voltage may be applled'between cathode a andanode block ill from a suitable source, for example, a battery 40 whosenegative terminal is connected to the cathode II and whose positiveterminal is connected to the anode block it and easing II which, sinceit is external to the cathode and liable to be touched by the hands ofan attendant, may be connected to ground. If desired. a varying voltage,e. g., a succession of pulses or a low frequency signal voltage of anydesired type, may be applied to are anode II to eifect modulation of theoscillaons.

An axial magnetic field may be supplied in any desired manner, as by acoil ll carrying a steady current in accordance with known practice.

In accordance with the invention, power may be abstracted by way oi aloop which links only the flux 28 which is mutual to two adjacentcavities II. A loop ofa convenient and suitable form may comprise a rod42 which extends radially inward from the outside through the casing 20into the end space 24 of the magnetron and there bends over to makecontact with the end face of the anode block In as at 44. Preferably,its course lies in a plane midway between two adjacent cavities il. Itmay be brought into the end space 24 by way of a flexible seal I. sothat the exact position at which its bent tip ll makes contact with theend face of the anode block Ill maybe varied at will simply by advancingor withdrawing the rod 42. Power withdrawn by way of this loop may beled over any suitable transmission path to a suitable load orutilization circuit schematically indicated by the resistor It.

The figures also illustrate the manner in which the mutual inductancecoupling loops of the invention may be applied to the adjustment or theoscillation frequency. To this end, a plurality of mutual inductancecoupling loops Ill, all of which may be alike and similar to the energyabstraction loop I! extend radially inward into the end space Itpreferably symmetrically disposed about the same. The outward extensionof each of these loops ll may form the inner conductor of a coaxial linewhose conductor is a tube 52 connected to the magnetron casing 20 at oneend and coupled to the inner conductor II by way of a conductive disc 54whose axial position is adjustable. A handle it. for example, ofinsulating material, may be provided to facilitate adjustment of thecoupling disc axially of the tube II. The inner conductors I. may beadvanced or withdrawn as desired to alter the amount of iiux linked bythe inwardly bent portion thereof by way of a suitable flexibleconnectiou.

Inasmuch as the separate resonant cavities ll are intercoupled with oneanother and also with the tuned coaxial lines ll, '2, II by way of themutual iiux It, it will be imderstood that alteratim of the effectiveelectrical length of these coaxiallines alters the frequency to whichthey areresonantand,whenthecouplingisgreater than a certain criticalvalue, the oscillation frequency of the device as a whole is altered.Such an arrangement provides a convenient means for adjusting theoscillation frequency of the magnetron precisely to a desired value forwhich it was designed, and so compensating for the elect of minuteerrors in manufacture.

For a given resonant frequency of the system composed of one resonantcavity and the channel which connects the same with the centralinteraction space, the length of the mutual iiux path between adjacentcavities I4 is most conveniently controlled by alteration in the shapeof i the cavity section. Thus, as the cross section of the cavity isshortened in the radial direction and elongated in a directionperpendicular thereto, the length or the mutual flux path betweenadjacent cavities is shortened, thereby increasing the mutual flux andthe intercavity coupling. Fig. 3 shows a simplified plan view of amagnetron having cavities ll of this modified form. They mayconveniently have the form of intersecting circles being constructed bydrilling two holes on centers which are spaced apart by less than theirdiameters.

Similarly, the intercavity couplings may be reduced, for a givenresonant frequency of the cavities, by the use of cavities of radiallyelongated cross sections. Such elongated cavities ll! may have radialsides as shown in Fig. 4 or they may be simple parallel-sides slots 62as shown in Fig. 5. Distribution of cavities in the manner shown inFigs. 4 and 5 by increasing the cavity surfaces, improves thedissipation of heat. tion, it permits the use of a greater number ofcavities, for a given amount of intercavity coupling, than is possiblewith an arrangement such as that shown in Fig. 3. For example, if thenumber of cavities of Fig. 3 were changed from 6 to 12 without otheralteration, adjacent sides of neighboring cavities would intersect,which would render them wholly inoperative. Thus, in a proper design,the cavity shape is intimately related with the number of cavities to beempioyed.

In the interests of simplicity, frequency adjusting loops Ill, 52, N areomitted from Figs. 3, 4 and 5, though they may be employed if desired.The magnetrons here represented may otherwise be similar to that ofFigs. 1 and 2, and like parts are designated by like referencecharacters Fig. 6 is a plan view of a modification in which the mutualinductance coupling loops of the invention are arranged for simultaneoussupply of oscillation energy to a common load. Four such loops 64 areprovided, symmetrically disposed about the periphery of the magnetrondischarge space I2. Provision may be made for varying the eflectiveareas of these loops in a manner similar to that hereinabove describedin connection with Fig. 1. Means for this purpose have. in the interestsof simplicity, been omitted from the drawings.

Inasmuch as the phases of the electromagnetic fields in successivecavities ll measured around the periphery of the magnetron, differsubstantially from each other, the currents withdrawn by these loops Mare by no means necessarily in phase with each other. Therefore, inorder that they may be effectively supplied as by coaxial lines 86 to acommon load, symbolically indicated in the figure by a resistor it,suitable means are preferably provided for bringing these currents intophase. Any suitable means will serve this purpose, the familiarso-called "trombone" slides Inaddi-- 7 10 being shown in the figure inseries with all but one of the lines Ci. Movement of the sliders Ialters the effective lengths of the lines It and therefore enables theoperator to bring the currents withdrawn by all of the loops 84 intocophasal relation.

Various modifications of the arrangement hereinabove described will sugest themselves to those skilled in the art for utilizing the mutualinductance coupling loops of the invention either for withdrawing power,for tuning adjustment, or otherwise, as desired.

What is claimed is:

1. In a high frequency magnetron device having a plurality of spacedanode surfaces interconnected by a like plurality of open-ended cavityresonators, and in which adjacent anode surfaces and cavities areintercoupled by high frequency electromagnetic fields existing in a,region adjacent the open ends of said resonators, means for withdrawingoscillatory energy from said device which comprises a conductorextending into the end space of said device and disposed adjacent saidopen resonator ends in a plane substantially midway between two adjacentcavities in position to link a part of the magnetic flux which is commonto said resonators andto avoid linking flux which is exclusivelyassociated with either one of said resonators singly.

2. The combination, in electromagnetic oscillation apparatus, whichcomprises at least two irequency-determining cavity resonators, saidresonators having openings so juxtaposed as to provide a path from oneof said resonators into another of said resonators for the mutualoscillatory magnetic flux which is common to both of said resonators,and means for abstracting energy from said resonators withoutintroducing excessive asymmetry into the field patterns of saidresonators, comprising a conductive loop disposed externally of both ofsaid resonators and substantially midway along said path in position tolink a portion of said mutual flux.

3. The combination, in electromagnetic oscillation apparatus, whichcomprises at least two frequency-determining cavity resonators, saidresonators having openings so juxtaposed as to provide a path from oneof said resonators into another of said resonators for the mutualoscillatory magnetic flux which is common to both of said resonators,said mutual flux providing a coupling between said resonators, and meansfor adjusting the common oscillation frequency of said coupledresonators to a desired value, comprising an auxiliary resonant devicedisposed externally of both of said resonators and coupled to saidmutual flux, and means for tuning said auxiliary resonant device.

4. The combination, in electromagnetic oscillation apparatus, whichcomprises at least two frequency-determining cavity resonators, saidresonators having openings so juxtaposed as to provide a path from oneof said resonators into another of said resonators for the mutualoscillatory magnetic flux which is common to both of said resonators,said mutual flux providing a coupling between said resonators, and meansfor adlusting the common oscillation frequency of said coupledresonators to a desired value, comprising a conductor disposedexternally of both of said resonators in position to link a portion ofsaid mutual flux, an auxiliary resonant device arranged to be excited bycurrents flowing in said conductor, and means for tuning said auxiliaryresonant device.

5. The combination, in ele oscillation apparatus, which comprises aplurality of frequency-determining cavity resonators, said resonatorshaving openings so mutually juxtaposed as to provide a path from each ofsaid resonators into another of said resonators for the mutualoscillatory magnetic flux which is common to both of said resonators,said mutual flux providing a coupling between said resonators, and meansfor abstracting energy from said resonators without introducingexcessive asymmetry into the field patterns of said resonators,comprising a plurality of conductive loops. each disposed externally ofsaid resonators in position to link a portion of the mutual fluxexisting along one of said paths.

6. The combination, in electromagnetic oscillation apparatus, whichcomprises a plurality of frequency-determining cavity resonators, saidresonators having openings so mutually juxtaposed as to provide a pathfrom each of said resonators into another of said resonators for themutual oscillatory magnetic flux which is common to both of saidresonators, said mutual flux providing a coupling between saidresonators. and means for adjusting the common oscillation frequency ofall of said intercoupied resonators to a desired value, comprising aplurality of auxiliary resonant devices disposed externally of saidresonators and coupled to said mutual flux, and means for tuning each ofsaid auxiliary resonator devices.

7. In combination with an electromagnetic oscillation device having atleast two adjacent open-ended frequency-determining cavity resonatorsarranged substantially parallel to each other and separated by aconductive wall, which resonators, when the device is in operation,support oscillatory electromagnetic fields which are at least partly inantiphase relation, means for abstracting energy from said device whichcomprises a conductor disposed in the plane of said separating wall andbeyond the end thereof which adjoins said open resonator ends in Doshtion to link a part of the magnetic flux which is common to saidresonators and to avoid link- 1118 flux whidh is exculsively associatedwith either one of said resonators singly.

8. In combination with a, high frequency magnetron device having aplurality of anode surfaces deflning a central discharge space and aplurality of intercoupled frequency-determining cavity resonatorsdisposed about said discharge space, means for withdrawing oscillatoryenergy from said device which comprises a plurality of coupling loopssymmetrically disposed with respect to the axis of said device, eacharranged to link a part of the oscillatory magnetic field of saidresonators without excessive loadin phase adjusting means coupled tocertain of said separate coupling loops for bringing currents withdrawnfrom said device y said loops into cophasal relation with each other,and common utilization means for said separately withdrawn currents.

9. In combination with a high frequency magnetron device having aplurality of anode surfaces defining a central discharge space and aplurality of open-ended frequency-determining cavity resonators disposedabout said discharge space, adjacent ones of said resonators beingseparated by walls each of which terminates in one of said anodesurfaces, means for adjusting the frequency of oscillation of saiddevice to a desired value, which comprises a plurality of conductorseach disposed in the plane of one of said separating walls and beyondthe end thereof which is adjacent to said open resonator ends inposition to link a part of the magnetic fiux which is common to saidresonators and extending outward of said device to become the innerconductor of a coaxial line, a tubular conductor surrounding each ofsaid outwardly extending parts, connected to an outer boundary wall ofsaid device and constituting the outer conductor of said coaxial line,and adjustable tuning means coupling each of said inner conductors tothe tubuiar member which surrounds it at a desired distance from theaxis of said device.

10. In a high frequency magnetron device having a plurality ofcircularly disposed spaced anode surfaces defining a central dischargespace, a plurality of open-ended cavity resonators disposed about saidcentral discharge space, an end plate which, with the ends of said anodesurfaces adjacent said open resonator ends defines a region in whichthere exists a high frequency electromagnetic flux intercoupling saidresonators, which flux emerges from one of said open resonator ends anddivides substantially evenly about a plane containing the axis of saidresonator, the flux portion on each side of said division plane passingto an adjacent resonator on the same side of said plane, an electrodewithin said discharge space, and means for applying a potential to saidlast-named electrode which comprises a conductor extending inward ofsaid device from the outside thereof and through said flux-containingregion to said last-named electrode, said conductor lying in saiddivision plane substantially throughout its length, whereby couplingbetween said conductor and said fill is reduced to a minimum.

11. In a high frequency electrical oscillator of the magnetron typecomprising a substantially cylindrical anode of conducting materialhaving therein a plurality of electromagnetically coupled cavityresonators each of which opens into a central space within said anode,said central space and resonator cavities opening at their ends intocommon end spaces defined by said anode, conductive end plates joined tosaid anode at both ends and providing therewith a substantially completeconducting envelope enclosing said resonator cavities and the chamberformed by said spaces, and adjustable power-output means comprising ahook-ended conductor extending inwardly of one of said end spaces andthrough its wall, lying in a plane substantially midway between twoadjacent cavity resonators in position to link electromagnetic fluxwhich is common to said two resonators, the hooked end of said conductorbeing in electrical contact with an end of said anode, said conductorbeing movable to facilitate adjustment of the amount of said fluxlinked.

12. In a high frequency electrical oscillator of the magnetron typecomprising a substantially cylindrical anode of conducting materialhaving therein a plurality of electromagnetically coupled cavityresonators each of which opens into a central space within said anode,said central space and resonator cavities opening at their ends intocommon end spaces defined by said anode. conductive end plates joined tosaid anode at both ends and providing therewith a substantially completeconducting envelope enclosin: said resonator cavities and the chamberformed by said spaces, and adjustable poweroutput means comprising aplurality of hookended conductors extending inwardly of one of said endspaces andthrough its wall, each lying in a plane substantially midwaybetween two adjacent cavity resonators in position to link magnetic fluxwhich is common to said two resonators, the hooked end of each of saidconductors being in electrical contact with an end of said anode, eachof said conductors being movable to facilitate adjustment of the amountof said flux linked, and tunable means for supplying the outputs of allof said conductors in phase to a common utilization circuit.

13. In a high frequency electrical oscillator of the magnetron typecomprising a substantially cylindrical anode of conducting materialhaving therein a plurality of electromagnetically coupled cavityresonators each of which opens into a central space within said anode,said central space and resonator cavities opening at their ends intocommon end spaces defined by said anode, conductive end plates joined tosaid anode at both ends and providing therewith a substantially completeconducting envelope enclosing said resonator cavities and the chamberformed by said spaces, and adjustable power-output means comprising aplurality of hook-ended conductors extending inwardly of one of said endspaces and through its wall, each lying in a plane substantially midwaybetween two adjacent cavity resonators in position to link magnetic fluxwhich is common to said two resonators, the hooked end of each of saidconductors being in electrical contact with an end of said anode, eachor said conductors being movable to facilitate adjustment of the amount01 said fiux linked, and being individually connected to the innerconductors of a like plurality of tunable coaxial transmission lines.

14. In a high frequency electrical oscillator of the magnetron typecomprising a substantially cylindrical anode of conducting materialhaving therein a plurality of electromagnetically coupled cavityresonators each of which opens into a central space within said anode,said central space and resonator cavities opening at their ends intocommon end spaces defined by said anode, conductive end plates joined tosaid anode at both ends and providing therewith a. substantiallycomplete conducting envelope enclosing said resonator cavities and thechamber formed by said spaces, said end plates having central, inwardlyextending portions for concentrating magnetic flux which is common totwo adjacent cavity resonators into the peripheral regions of said endspaces, and adjustable power-output means as cylindrical anode ofconducting material having therein a plurality of electromagneticallycoupled cavity resonators each of which opens into a central spacewithin said anode, said central space and resonator cavities opening attheir 0 ends into common end spaces defined by said anode, conductiveend plates joined to said anode at both ends and providing therewith asubstantially complete conducting envelope enclosing said resonatorcavities and the chamber formed by said spaces, said end plates having11 central, inwardly extending portions for concentrating magnetic fluxwhich is common to two adjacent cavity resonators into the peripheralregions oi said end spaces, and adJustable poweroutput means comprisinga plurality of hookended conductors extending inwardly of one oi saidend spaces and through its wall, lying in a plane substantially midwaybetween two adia- 12 cent cavity resonators in position to link magneticflux in said peripheral region which is common to said two resonators,the hooked end 01' each of said conductors being in electrical contactwith an end oi said anode, each of said conductors being movable tofacilitate adjustment of the amount of said flux linked.

JAMES B. RISK.

Disclaimer 2,411,15L-James B. Fisk, Madison, N. J. OUTPUT COUPLING nonHmn-Fnsqunncr Osornm'rons. by the assignee,

Patent dated N av. 19, 1946.

Bell Telephone Laoratories, Incorporated.

Disclaimer filed June 2, 1950,

Hereba enters this disclaimer to claims 1, 2, and 7 of said ate t l p nGazefle, Sept. 6, 1950.]

11 central, inwardly extending portions for concentrating magnetic fluxwhich is common to two adjacent cavity resonators into the peripheralregions oi said end spaces, and adJustable poweroutput means comprisinga plurality of hookended conductors extending inwardly of one oi saidend spaces and through its wall, lying in a plane substantially midwaybetween two adia- 12 cent cavity resonators in position to link magneticflux in said peripheral region which is common to said two resonators,the hooked end 01' each of said conductors being in electrical contactwith an end oi said anode, each of said conductors being movable tofacilitate adjustment of the amount of said flux linked.

JAMES B. RISK.

Disclaimer 2,411,15L-James B. Fisk, Madison, N. J. OUTPUT COUPLING nonHmn-Fnsqunncr Osornm'rons. by the assignee,

Patent dated N av. 19, 1946.

Bell Telephone Laoratories, Incorporated.

Disclaimer filed June 2, 1950,

Hereba enters this disclaimer to claims 1, 2, and 7 of said ate t l p nGazefle, Sept. 6, 1950.]

